160. 相交链表

/**
 * Definition for singly-linked list.
 * function ListNode(val) {
 *     this.val = val;
 *     this.next = null;
 * }
 */

/**
 * @param {ListNode} headA
 * @param {ListNode} headB
 * @return {ListNode}
 */
var getIntersectionNode = function (headA, headB) {
  let curA = headA
  let curB = headB
  const set = new Set()
  let count = 0
  while (curA || curB) {
    if (curA) {
      set.add(curA)
      count++
      if (set.size !== count) {
        return curA
      }
      curA = curA.next
    }
    if (curB) {
      set.add(curB)
      count++
      if (set.size !== count) {
        return curB
      }
      curB = curB.next
    }
  }
  return null
}